Semiconductor die packages with standard ball grid array footprint and method for assembling the same

ABSTRACT

Apparatus and methods for forming semiconductor assemblies. An interposer includes a perimeter wall surrounding at least a portion of an upper surface thereof to form a recess. An array of electrical connection pads is located within the recess. A semiconductor die can be flip chip attached to the interposer by at least partial insertion of the semiconductor die within the recess with discrete conductive elements between bond pads of the semiconductor die and electrical connection pads of the interposer. The electrical connection pads communicate with a number of other electrical contact pads accessible elsewhere on the interposer, preferably on a lower surface thereof. A low viscosity underfill encapsulant is disposed between the semiconductor die and the interposer and around the discrete conductive elements by permitting the same to flow into the space between the die and the perimeter wall. The encapsulant may form an underfill or substantially encapsulate the semiconductor die within the recess of the interposer.

FIELD OF THE INVENTION

The present invention relates to ball grid array (“BGA”) semiconductorpackages and methods of attaching, encapsulating and evaluating thesame. In particular, the present invention relates to interposers formounting a BGA semiconductor die to a carrier substrate with which theBGA semiconductor die is in electrical communication, such that anunderfill encapsulant may be flowed between the BGA semiconductor dieand the interposer. The BGA semiconductor die may be encapsulated withinthe interposer to form a complete semiconductor die package. Theinterposer may be constructed such that semiconductor die havingdifferent patterns of BGAs may be mounted on identical substrateswithout a need for substrate alteration.

BACKGROUND

Definitions: The following terms and acronyms will be used throughoutthe application and are defined as follows:

BGA—Ball Grid Array: An array of minute solder balls disposed on anattachment surface of a semiconductor die, interposer, or semiconductorpackage wherein the solder balls are reflowed for simultaneousattachment and electrical communication with a substrate, such as aprinted circuit board.

COB—Chip on Board: The techniques used to attach semiconductor dice tosubstrates, including flip chip attachment, wirebonding, and tapeautomated bonding (“TAB”).

Flip Chip: A semiconductor die or chip having bumped bond pads on theactive surface of the die and is intended for facedown mounting.

Flip Chip Attachment: A method of attaching a semiconductor die to asubstrate in which the die is flipped so that the connecting conductorpads on the active surface of the die are set on mirror image pads onthe substrate and bonded by reflowing solder.

Glob Top: A glob of encapsulant material (usually epoxy or silicone or acombination thereof) surrounding a semiconductor die in the COB assemblyprocess.

Low Viscosity Encapsulant: An encapsulant material suitable for use asan underfill (usually epoxy or silicone or a combination thereof) which,prior to curing, has a relatively low viscosity, such that it may bedirected to flow into and through an array of connecting bond pads of asemiconductor die attached to a substrate, with substantially no voidsleft therein, without the use of a pressure differential.

PGA—Pin Grid Array: An array of small pins extending substantiallyperpendicularly from the major plane of a semiconductor die, interposer,or semiconductor package, wherein the pins conform to a specificarrangement for attachment to a substrate.

SLICC—Slightly Larger than Integrated Circuit Carrier: An array ofminute solder balls disposed on an attachment surface of a semiconductordie, interposer, or semiconductor package similar to a BGA, but having asmaller solder ball pitch and diameter than a BGA.

Flip chip attachment consists of attaching a semiconductor die,generally having a BGA, a SLICC or a PGA, to a printed circuit board orother substrate. With the BGA or the SLICC, the solder ball arrangementon the semiconductor die must be a mirror image of the connecting bondpads on the substrate such that a precise connection is made. Thesemiconductor die is bonded to the substrate by reflowing the solderballs. With the PGA, the pin arrangement of the semiconductor die mustbe a mirror image of the pin recesses on the substrate. After insertion,the semiconductor die is generally bonded by soldering the pins intoplace.

Once the semiconductor die has been flip chip attached to the substrate,an underfill encapsulant is generally disposed between the semiconductordie and the substrate. The underfill encapsulant is generally a fluidepoxy that may be flowed into the connection space between thesemiconductor die and substrate, laterally between the solderedelectrical connections, Typically, the underfill encapsulant is allowedto flow until fillets of underfill encapsulant are formed around thesides of the semiconductor die. In order to form the fillets and toprevent the underfill encapsulant from flowing further and coveringother portions of the substrate, thereby reducing the “real estate” (diesurface area) used by the semiconductor die connection, it has beennecessary to use underfill encapsulants which have a relatively highviscosity.

Once cured, the underfill encapsulant serves multiple functions. Itcompensates for the difference in coefficient of thermal expansionbetween the substrate and the semiconductor die. It also protects thesolder bumps from environmental contaminants. However, flowing anunderfill encapsulant with relatively high viscosity into the connectionspace raises further problems. More viscous underfill encapsulants areoften unable to flow in between all the connections within theconnection space. Empty areas, or voids, occurring when bubbles aretrapped within the connection space are common. Delaminations, where thehigh viscosity underfill encapsulant fails to wet and adhere to asurface, also occur. Such defects can lead to the early failure of thesemiconductor die when in operation.

Attempts have been made to reduce the number of defects in theunderfilling process. Typically, a vacuum is applied to facilitate theflow of underfill encapsulant into the connection space. Alternatively,or in addition to the application of a vacuum, a highly viscousunderfill encapsulant may be injected under elevated pressure. Evenwhere these techniques are used, defects can still occur. Applying avacuum or elevated pressure can stress the solder connections, resultingin weakening or breakage thereof. The manufacturing cost of the packageis also increased as additional processing steps as well as additionalequipment for maintaining and applying the pressure differences arerequired.

With wire-bond or TAB adapted dies, a molded carrier ring may be used toprotect a portion of the leads as they extend out from the semiconductordie. This is accomplished by placing a molded carrier ring around thedie, with the leads protruding therefrom, then filling the moldedcarrier ring with an encapsulant material. The ends of the leadsprotruding from the ring are available for testing or connection to asubstrate. While the die itself is protected, the exposed lead endsremain susceptible to breakage, moisture and contamination. Even thislimited protection cannot be used with flip chip adapted semiconductordie, as the connection pads do not extend out parallel to the plane ofthe die.

Therefore, it would be advantageous to develop an apparatus and methodthat allow for use of a relatively low viscosity underfill encapsulantwith flip chip attachment for semiconductor dice, reducing the rate ofunderfill defects while eliminating the need for a vacuum or pressurizedinjection. It would further be advantageous for such an apparatus andmethod to provide a standard connection pattern allowing forsemiconductor dice having different connection patterns to be attachedto a common substrate having a single set of connection terminals.

BRIEF SUMMARY OF THE INVENTION

The present invention includes apparatus and methods for preparingsemiconductor packages, or assemblies. An interposer having a perimeterwall surrounding a recess on an upper surface thereof includes an arrayof electrical connection pads within the recess. A semiconductor die canbe flip chip attached, making electrical contact through the electricalconnection pads to a number of other electrical contacts accessibleelsewhere on the interposer, preferably on the lower surface thereof. Alow viscosity underfill encapsulant is disposed between thesemiconductor die and the interposer by flowing into the space betweenthe die and the perimeter wall of the interposer. The underfillencapsulant flows throughout the connection array by capillary action,without the assistance of either positive or negative pressure. Theunderfill encapsulant may be flowed until the underfill is complete, oruntil the entire semiconductor die is encapsulated within theinterposer.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which depict the best mode presently known for carryingout the invention:

FIG. 1 is a perspective view of a semiconductor die which is about to beattached to an interposer in accordance with the present invention toform a semiconductor assembly made in accordance with the presentinvention;

FIG. 2 is a perspective view of the semiconductor assembly of FIG. 1,after the semiconductor die has been positioned in the recess of theinterposer;

FIG. 3 is a side cross-sectional view of one embodiment of asemiconductor assembly made in accordance with the principles of thepresent invention;

FIG. 3A is a side cross-sectional view of another embodiment of theupper electrical connection pads and electrical vias of a semiconductorassembly made in accordance with the principles of the presentinvention;

FIG. 4 is a side cross-sectional view of an alternative embodiment ofsemiconductor assembly made in accordance with the principles of thepresent invention; and

FIG. 5 is a side cross-sectional view of another embodiment of asemiconductor assembly made in accordance with the principles of thepresent invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made to drawing FIG. 1. Several components of asemiconductor assembly 10 in accordance with the principles of thepresent invention are depicted, in an unassembled manner. Asemiconductor die 12, also referred to as a semiconductor chip, featuresa number of solder balls 14 attached to the bond pads 16 of the activesurface (face) 18 thereof. As depicted, the bond pads 16 are arranged ina grid array connection pattern that, along with solder balls 14,facilitates a BGA-type connection, but it will be appreciated that aSLICC, a PGA, or any other suitable connection method may be used inconnection with the bond pads 16.

An interposer 20 is used for attachment to the semiconductor die 12.Interposer 20 includes an upper surface 22, which features a perimeterwall 24 substantially encircling a recess 26 formed within upper surface22 and configured to at least partially receive a semiconductor die 12.As shown in FIG. 1, perimeter wall 24 may form a complete structure, butmay alternatively include small gaps (shown in dashed lines) therein.The perimeter wall 24 may be formed continuous with the outer edge 23 ofthe interposer 20 or it may be inset, as depicted by FIG. 1, to form aledge or shoulder 25 at one or more outer edges 23 of the interposer 20.It is preferred that the interposer 20 be sized as closely as possibleto the semiconductor die 12. This results in a semiconductor assembly 10having only a marginally larger size than the bare semiconductor die 12,conserving area on a substrate to which the entire semiconductorassembly 10 is attached. The thickness of such a semiconductor assembly10 may also be only marginally thicker than the bare semiconductor die12.

Within the recess 26 are a number of upper electrical connection pads28, which are arranged in a pattern corresponding to the pattern of bondpads 16 of the semiconductor die 12. When the semiconductor die 12 isinstalled in the recess 26, the solder balls 14 of the BGA, asillustrated in the embodiment of the invention of drawing FIG. 1, areplaced on top of and in contact with upper electrical connection pads28. The installation may be accomplished by inverting the semiconductordie 12 over the recess 26, as shown by arrow A.

Turning to drawing FIG. 2, the components of the semiconductor assembly10 illustrated in FIG. 1 are shown with the semiconductor die 12installed in the recess 26 of the interposer 20 and within the confinesof the perimeter wall 24. The bond pads 16 (FIG. 1) of the semiconductordie 12 are positioned above their corresponding upper electricalconnection pads 28 (FIG. 1) within the recess 26 of the interposer 20.In embodiments using a BGA or SLICC arrangement, the semiconductor die12 may be joined to the interposer 20 and the bond pads 16 electricallyconnected to the upper electrical connection pads 28 by reflowing thesolder balls 14.

As shown in drawing FIG. 2, when the semiconductor die 12 is installedin the recess 26 of the interposer 20, a flow space 30 is locatedbetween the perimeter wall 24 of the interposer 20 and the outerperiphery 13 of the semiconductor die 12, providing access to the recess26.

Illustrated in drawing FIG. 3 is a cross-sectional view of asemiconductor assembly 40 including a semiconductor die 42 installed ina recess 56 of an interposer 50. Perimeter wall 54 is formed as theouter edge of the interposer 50 in the embodiment of the inventionillustrated in drawing FIG. 3. The bond pads 44 of the semiconductor die42 are attached to the upper electrical connection pads 58 within therecess 56 of the interposer 50 by reflowed solder connections 46. Theupper electrical connection pads 58 communicate with lower electricalconnections 60 on the lower surface 51 of the interposer 50 throughelectrical traces 59 that pass through the interposer 50.

While it will be appreciated that electrical traces 59 may be formedfrom any suitable electrically conductive material, and may beconstructed in any suitable manner known to those skilled in the art, insome possible embodiments of the present invention, the interposer 50may be formed using an epoxy-glass laminate such as FR-4. In suchembodiments, the interposer 50 may be formed by laminating layers ofFR-4 together to form the surfaces, perimeter walls 54 and recess 56 ofthe interposer 50. Upper electrical connection pads 58 and lowerelectrical connections 60 may be formed through the additive orsubtractive etching of a conductive layer upon the laminate. Electricaltraces 59 through the interposer 50 body may be formed throughlaminating conductive material within the interposer 50. Alternatively,holes or recesses may be created within the interposer during laminationthereof or by mechanical means such as drilling. The holes may be usedas vias 62 (FIG. 3A), or may be filled with a conductive material toform the electrical traces 59.

Illustrated in drawing FIG. 3A is another alternative embodimentstructure for the upper electrical connection pads 58 and the electricaltraces 59 illustrated in drawing FIG. 3. A number of vias 62 areaccessible within the recess 56 of the interposer 50, in a patterncorresponding to the bond pads 44 of the semiconductor die 42. Vias 62connect to the lower electrical connections 60 of the interposer 50. Asshown, once the solder connections 46 are formed by reflowing, the vias62 are filled with solder, electrically coupling the bond pads 44 to thelower electrical connections 60.

Returning to drawing FIG. 3, the lower electrical connections 60 arepreferably formed into a standard pattern to provide a standardizedconnection “footprint,” facilitating the electrical connection ofsemiconductor assemblies 40 including semiconductor dice having bondpads 44 of various different connection patterns to a substrate, or atesting device, with a fixed connection pattern. Interposer 50 mayinclude upper electrical connection pads 58 that are formed tocorrespond to different bond pad arrangements of different semiconductordice. This can be accomplished in a number of ways. One set of alternateupper electrical connection pads, represented by 58A and 58B,communicates with a single lower electrical connection 60 throughelectrically conductive traces 59A and 59B. Another set of alternateelectrical connection pads represented by 58C and 58D are connected byan electrical trace 61 on the surface of the interposer recess 56,resulting in connection to a single electrically conductive trace 59.Electrical trace 61 may be formed at the same time as the upperelectrical connection pads 58. Other possible alternatives includealternate sets where a number of upper electrical connection pads 58 areconnected to one or more electrically conductive traces 59. Alternatesets may be formed in connection with vias 62 (FIG. 3A) throughconnection of an upper electrical connection pad 58 to the via 62through an electrical trace 61 or 59, or by a channel 63 (FIG. 3A) whichallows solder to flow to the via 62. It will be appreciated that anumber of alternate sets of upper electrical connection pads 58 can beformed into alternate arrays and that, while alternate electricalconnections include alternate pairs of upper electrical connections,they may also include three, four or any other number of sets ofalternate electrical connection pads.

The arrangement of the lower electrical connections 60 in a single,standard footprint allows for decreased production costs in assemblingproducts utilizing the complete packaged semiconductor assemblies 40formed as part of the present invention. The interposer 50 may alsoinclude additional electrical components needed to allow alternativesemiconductor dies 42 to be functionally used in a completesemiconductor assembly 40 including the interposer 50.

The space 70 between the semiconductor die 42 and the interposer 50 isfilled by flowing an underfill encapsulant thereinto. Arrows 72 show theflow of the underfill encapsulant. The perimeter walls 54 act torestrain the flow of the underfill encapsulant to locations within therecess 56 and thereover. The distance between the perimeter wall 54 andthe semiconductor die 42 determines the rate at which the underfillencapsulant may flow through and into the space 70, and between thesemiconductor die 42 and the upper surface of the interposer recess 56.Preferably, the distance between each side of the semiconductor die 42and its corresponding perimeter wall 54 is substantially equal, creatingsubstantially equal flow restriction along each of the side surfaces ofthe semiconductor die 42. This allows for a low viscosity underfillencapsulant to be used and to be flowed in along two or more sides ofthe semiconductor die 42 at the same time. Preferably, the underfillencapsulant is flowed into the space 70 along the entire perimeter ofthe semiconductor die 42. The low viscosity underfill encapsulant willflow laterally between the soldered electrical connections 46 betweenthe semiconductor die 42 and the interposer 50 by capillary action, or“wicking,” to substantially fill the space 70. Flow of the underfillencapsulant is increased relative to a higher viscosity underfillencapsulant. The underfill encapsulant does not need to be injected atelevated pressure and no vacuum is required. In this way, the occurrenceof underfill defects can be reduced, while additional steps andequipment are not required.

Illustrated in drawing FIG. 4 is a cross-sectional view of asemiconductor assembly 80 made in accordance with the principles of thepresent invention. A semiconductor die 82 is installed in flip chipfashion at least partially within a recess 96 of an interposer 90 thatincludes a perimeter wall 92. An underfill encapsulant 102 has beenflowed as described above between the semiconductor die 82 and theinterposer 90. The electrical connections 86 between the bond pads 84 ofthe semiconductor die 82 and the upper electrical connection pads 98 ofthe interposer 90 are completely encapsulated, protecting theconnections from moisture and contamination. The underfill encapsulant102 has been flowed to the point where the entire first surface 83 ofthe semiconductor die 82 was wetted and thereby bound thereto. Thisreduces the physical stress on the electrical connections while leavingthe second surface 85 of the semiconductor die 82 exposed. A heat sink87 (shown in dashed lines), or other structure, may then be installedupon the second surface 85 of the semiconductor die 82. In embodimentsof the present invention where the underfill encapsulant 102 extendsonly to the first surface 83 of the semiconductor die 82, it ispreferred that the perimeter wall 92 be equal to or less than the heightof the second surface 85 of the installed semiconductor die 82 tofacilitate the installation of a heat sink or other structure onto thesecond surface 85 of semiconductor die 82.

As shown in drawing FIG. 4, the underfill encapsulant 102 may fill theentire available space around the semiconductor die 82, instead offorming fillets around the base of the semiconductor die 82. The presentinvention provides for the use of underfill encapsulants of such lowviscosity that such fillets may not form. This increases the ability ofthe encapsulant to flow throughout the connections, reducing theoccurrence of defects. It will be appreciated, however, that theprinciples of the present invention extend to the use of lower viscosityunderfill encapsulants that retain the ability to form fillets, and theuse of such underfill encapsulants is within the scope of the presentinvention.

Also illustrated in drawing FIG. 4 is an interposer 90 including a ledge95 on the upper surface thereof and located outside the perimeter wall92. In some variations of interposer 90, ledge 95 may carry additionalelectrical connection pads that may provide additional connection pointsor testing points for the semiconductor assembly 80.

Illustrated in drawing FIG. 5 is a cross-sectional view of anotherembodiment of a semiconductor assembly 110, made in accordance with theprinciples of the present invention. A semiconductor die 112 ispositioned within a recess 126 of and flip chip bonded to an interposer120. An underfill encapsulant 140 has been flowed between thesemiconductor die 112 and the interposer 120, as described above. Theelectrical connections 116 between the bond pads 114 of thesemiconductor die 112 and their corresponding upper electricalconnection pads 128 of the interposer 120 are substantiallyencapsulated, protecting the electrical connections 116 from moistureand contamination. Unlike the embodiment of the present inventionillustrated in drawing FIG. 4, in this embodiment of the invention, oncethe first surface 113 of the semiconductor die 112 is wetted by theunderfill encapsulant 140, further underfill encapsulant is flowed intothe recess 126, until the second surface 115 of the semiconductor die112 is also encapsulated within the underfill encapsulant 140. Theperimeter wall 124 is greater in height than the second surface 115 ofthe installed semiconductor die 112 to facilitate encapsulation of thesecond surface 115.

Once the underfill encapsulant 140 has cured, the semiconductor die 112of the embodiment of the invention illustrated in drawing FIG. 5 iscompletely encapsulated, protecting it from moisture entry,contamination, and delamination. A separate glob top epoxy is notneeded, eliminating both an extra step in package preparation and theneed for additional materials.

A semiconductor assembly made in accordance with the principles of thepresent invention, such as those embodiments of the present inventionillustrated in drawing FIGS. 3, 4 and 5, among others, may be attachedor secured relative to a substrate (not shown) via discrete conductiveelements secured to the lower electrical connection pads (represented at60, 100 and 130 in the respective drawings). The substrate can be partof a final product into which the assembly is to be incorporated, or itmay be for testing the semiconductor die. Alternatively, the assemblymay be tested through the lower electrical contacts prior to attachmentto a substrate. The assembly may be attached to the substrate using anyCOB technique known to those skilled in the art, but it is preferred touse a flip chip type of attachment, preserving the advantages of thisspace-saving attachment, while including the advantages of the presentinvention.

In accordance with the description provided herein, the presentinvention includes a method of forming a semiconductor assemblyincluding an underfilled flip chip mounted die and perimeter walledinterposer, comprising:

providing an interposer having an upper surface and an opposite lowersurface, a perimeter wall protruding from the upper surface andsubstantially encircling at least a portion of the upper surface to forma recess, the recess having at least one upper electrical contact padlocated therein;

providing a semiconductor die having a first surface and a secondsurface, the first surface including at least one bond pad thereon;

positioning the semiconductor die at least partially within thereceptacle of the interposer within the recess such that the at leastone bond pad is in electrical communication with the at least one upperelectrical contact pad on the upper surface of the interposer and atleast some of the surface area of the upper surface of the interposer isaccessible between a periphery of the semiconductor die and theperimeter wall of the interposer; and

disposing an underfill encapsulant onto the accessible surface area suchthat the underfill encapsulant flows between the first surface of saidsemiconductor die and the upper surface of said interposer between theperiphery of the semiconductor die and the perimeter wall, encapsulatingthe at least one upper electrical contact pad and the at least one bondpad within the underfill encapsulant.

Further, it will be appreciated that the present invention includes amethod of forming a semiconductor assembly including an interposer witha standardized footprint comprising:

providing an interposer comprising an upper surface, a perimeter wallsubstantially encircling the upper surface, and a recess formed by theupper surface and the perimeter wall having at least two upperelectrical contacts located on the upper surface, within the recess, apair of alternate upper electrical contacts, a lower surface having atleast a first lower electrical connection located thereon, at least thefirst lower electrical connection in electrical connection with a firstupper electrical connection and a second upper electrical connection;

positioning a semiconductor die at least partially within the recess andelectrically connecting at least one bond pad thereof to one of the atleast two upper electrical contacts.

It is readily evident that semiconductor assemblies made in accordancewith the principles of the present invention have a reduced number ofdefects and are capable of being manufactured with reduced steps inassembly. Perimeter walled interposers may be sized only slightly largerthan the semiconductor chip and may include a flip chip type ofattachment array or other connection pattern on the lower surfacethereof. Such an arrangement conserves real estate by allowing flip chipattachment of the entire structure to a substrate in an area onlyslightly larger than the semiconductor die. The need for applying apositive or negative pressure during assembly to facilitate flow of theunderfill encapsulant and the need for a glob top encapsulant areeliminated, resulting in lower manufacturing costs.

The array of electrical connection pads in the interposer recess can bedesigned to facilitate electrical connection of the interposer with anumber of alternative bond pad arrangements of different semiconductordice. The resulting packages have a common footprint for attachment to asubstrate. Alternative semiconductor dice capable of performing the sameor similar functions can be easily substituted in the semiconductorassembly, without a need for changing the connection pattern on thesubstrate. This allows for more efficient installation, or testing, ofthe semiconductor assemblies, reducing the potential costs and timeinvolved in utilizing the equivalent assemblies in the manufacture ofproducts.

It will be apparent that details of the apparatus and methods hereindescribed can be varied considerably without departing from the conceptand scope of the invention. The claims alone define the scope of theinvention as conceived and as described herein.

What is claimed is:
 1. A semiconductor assembly comprising: aninterposer including an upper surface, a perimeter wall substantiallyencircling said upper surface to form a recess, said perimeter walldisposed to create a flow space between itself and at least a portion ofan edge of a semiconductor die when said semiconductor die is positionedin said recess, and a lower surface having at least a first lowerelectrical connection pad located thereon; and a semiconductor diepositioned at least partially within said recess, said semiconductor dieincluding a first surface positioned adjacent said upper surface of saidinterposer; and a first set of alternate upper electrical contact padslocated in said recess, each upper electrical contact pad of said firstset of alternate upper electrical contact pads electrically connected toa first lower electrical connection pad through an electricallyconductive trace.
 2. The semiconductor assembly of claim 1, wherein saidfirst set of alternate upper electrical contact pads comprises a firstupper electrical contact pad and a second upper electrical contact pad.3. The semiconductor assembly of claim 2, wherein said first upperelectrical contact pad and said second upper electrical contact pad arein electrical communication with said first lower electrical connectionpad.
 4. The semiconductor assembly of claim 3, wherein said first upperelectrical contact pad and said second upper electrical contact pad arepositioned such that a first bond pad on said semiconductor die is inelectrical communication with said first lower electrical correction padthrough communication with one of said first and second upper electricalcontact pads.
 5. The semiconductor assembly of claim 1, furthercomprising at least a second set of alternate upper electrical contactpads located in said recess.
 6. The semiconductor assembly of claim 5,wherein said at least a second set of alternate upper electrical contactpads comprises at least two second alternate upper electrical contactpads.
 7. The semiconductor assembly of claim 6, wherein said at leasttwo second alternate upper electrical contact pads are in electricalcommunication with a second lower electrical connection pad.
 8. Thesemiconductor assembly of claim 7, wherein said at least two secondalternate upper electrical contact pads are positioned such that a bondpad on said semiconductor die is in electrical communication with saidsecond lower electrical connection pad through communication with one ofsaid at least two alternate upper electrical contact pads.
 9. Thesemiconductor assembly of claim 5, further comprising a plurality ofupper electrical contact pads comprising three or more sets of alternateupper electrical contact pads and an away of lower electrical connectionpads formed into a standard array, individual bond pads on saidsemiconductor die in electrical communication with said standard arrayof lower electrical connection pads through communication withindividual alternate upper electrical conduct pads of said sets ofalternate upper electrical contact pads.
 10. The semiconductor assemblyof claim 1, wherein said perimeter wall is at least substantially equalin height to said semiconductor die.
 11. The semiconductor assembly ofclaim 10, wherein said perimeter wall is greater in height than saidsemiconductor die.
 12. The semiconductor assembly of claim 1, furthercomprising an underfill encapsulant disposed between said first surfaceof said semiconductor die and said upper surface of said interposer. 13.The semiconductor assembly of claim 12, wherein said underfillencapsulant is disposed along said upper surface of said interposerbetween a periphery of said semiconductor die to said perimeter wall.14. The semiconductor assembly of claim 12, wherein said underfillencapsulant comprises a material flowable between said semiconductor dieand said interposer to encapsulate a bond pad on said semiconductor dieand an upper electrical contact pad disposed in said recess of saidinterposer, without use of a pressure differential.
 15. Thesemiconductor assembly of claim 12, wherein said semiconductor die issubstantially encapsulated within said underfill encapsulant.
 16. Thesemiconductor assembly of claim 1, further comprising a solder balldisposed on said at least first lower electrical connection pad.
 17. Asemiconductor assembly comprising: an interposer including an uppersurface, a perimeter wall substantially encircling said upper surface toform a recess, said perimeter wall disposed to create a flow spacebetween itself and at least a portion of an edge of a semiconductor diewhen said semiconductor die is positioned in said recess, and a lowersurface having at least a first lower electrical connection pad locatedthereon; and a semiconductor die positioned at least partially withinsaid recess, said semiconductor die including a first surface positionedadjacent said upper surface of said interposer; and a first set ofalternate vias located in said recess, each of said first set ofalternate vias in electrical communication with a first lower electricalconnection pad.
 18. The semiconductor assembly of claim 17, wherein saidfirst set of alternate vias comprises a first via and a second via. 19.The semiconductor assembly of claim 18, wherein said first via and saidsecond via run from said upper surface of said interposer to said atleast a first lower electrical connection pad.
 20. The semiconductorassembly of claim 19, wherein said first via and said second via arepositioned such that a first bond pad on said semiconductor die is inelectrical communication with said at least first lower electricalconnection pad through one via of said first via and said second via.21. The semiconductor assembly of claim 17, wherein said perimeter wallis at least substantially equal in height to said semiconductor die. 22.The semiconductor assembly of claim 21, wherein said perimeter wall isgreater in height than said semiconductor die.
 23. The semiconductorassembly of claim 17, further comprising an underfill encapsulantdisposed between said first surface of said semiconductor die and saidupper surface of said interposer.
 24. The semiconductor assembly ofclaim 23, wherein said underfill encapsulant is disposed along saidupper surface of said interposer between a periphery of saidsemiconductor die to said perimeter wall.
 25. The semiconductor assemblyof claim 23, wherein said underfill encapsulant comprises a materialflowable between said semiconductor die and said interposer toencapsulate a bond pad on said semiconductor die and an upper electricalcontact pad disposed in said recess of said interposer, without use of apressure differential.
 26. The semiconductor assembly of claim 23,wherein said semiconductor die is substantially encapsulated within saidunderfill encapsulant.
 27. The semiconductor assembly of claim 17,further comprising a solder ball disposed on said at least first lowerelectrical connection pad.